The current invention is in the field of the position tracking and control systems.
In the available art of position tracking and control systems, the three dimensional position coordinates of the mobile object can be determined in a variety of ways. In recent years, the global positioning satellite (GPS) receivers and the receivers that use the alternative satellite systems, like GLONASS system, came of age and began to proliferate widely. The autonomous navigational system that includes the satellite receiver and a navigational computer can achieve the 10-meter level of accuracy in the position determination of the mobile object.
The differential navigation systems that utilize the differential corrections in addition to the satellite signals can determine the positional information with the meter-range accuracy. The real-time kinematic (RTK) GPS systems that are capable of utilizing in real time not only code abut also the carrier information transmitted from satellites can achieve the centimeter level of accuracy in the position determination of the mobile object.
However, the millimeter level of accuracy is still beyond the reach of the satellite navigational systems. The prior art rotating laser-based systems can define the plane level (Z-plane) with a millimeter level of accuracy. However, these prior art laser-based systems can not be used for the purposes of three dimensional navigation of mobile objects because they are configured to determine only one (Z) coordinate of a mobile object. What is needed is the laser-based system that can be used for the purposes of precise three dimensional navigation of a mobile object.
To address the shortcomings of the available art, the present invention provides a method and a system for precise laser-based three dimensional navigation and tracking of a mobile object.
One aspect of the present invention is directed to a three dimensional multi-unit laser control and tracking system. In one embodiment, the system comprises: (1) a light beacon generating a rotating beam of laser light to cover a three-dimensional site area, and (2) a signal system capable of detecting the laser beam reflected from at least one mobile unit. The signal system generates at least one communication signal including an ID and a positional information of each mobile unit and transmits each communication signal to each mobile unit. Each mobile unit by matching its ID and the timing of reflection of the laser beam is capable to recover its positional information from one such communication signal.
In an alternative embodiment, a three dimensional multi-unit laser control and tracking system comprises: (1) a light beacon generating a rotating and scanning beam of laser light to cover a three-dimensional site area, (2) at least one mobile unit, (3) a signal system capable of detecting the laser beam reflected from each mobile unit, and (4) at least one receiver mounted on each mobile unit. Each mobile unit provides its identification number (ID) upon sensing and reflecting the incoming laser beam. The signal system generates at least one communication signal including an ID and a positional information of one mobile unit and transmits this information to each mobile unit. Each mobile unit by matching its ID and the timing of reflection of the laser beam is capable to recover its positional information from one such communication signal.
In the preferred embodiment, the mobile unit further includes an intelligent reflector including a memory chip and a processor. The memory chip includes the ID of one mobile unit. The processor determines the exact time when the laser beam illuminated the intelligent reflector. In one embodiment, the intelligent reflector transmits the ID of the mobile unit and the time of illumination to the signal system using the incoming rotating laser beam.
In an alternative embodiment, the signal system further includes a first communication system used to transmit the ID and the time of illumination by the rotating laser beam from each mobile unit to the signal system. The first communication system includes: (1) a laser system generating a second laser beam utilized to transmit the ID and the time of illumination from each mobile unit to the signal system, or a radio communication system used for the same purposes. In the preferred embodiment, the signal system further includes a signal processor. The signal processor is utilized to calculate the three-dimensional coordinates for each mobile unit by determining the angular coordinates of the laser beam reflected from each mobile unit, by determining the distance between the light beacon and each mobile unit, and by matching the positional information for each mobile unit with the ID and the time of illumination by the rotating laser beam.
In the preferred embodiment, the signal system further includes a second communication system used to transmit to each mobile unit its positional information. The second communication system can include a laser source generating a third laser beam used to transmit the positional information to each mobile unit, or a radio communication system used for the same purposes.
In one embodiment, the laser beacon further includes a laser source, a scanning system for scanning the laser source within a vertical plane for generating a laser beam, and a rotating system for rotating the laser beam within the horizontal plane. The scanning system as well as the rotating system can be implemented using the mechanical and/or optical means.
Another aspect of the present invention is directed to a method for control and tracking at least one mobile unit employing a three dimensional laser system. The method comprises the following steps: (1) generating a rotating beam of laser light capable of covering a three-dimensional site area; (2) detecting the laser beam being sequentially reflected from each mobile unit; (3) receiving the ID and the time of illumination of each mobile unit by the signal system; (4) generating the positional information for each mobile unit; (5) matching the positional information, ID, and the time of illumination for each mobile unit; and (6) communicating to each mobile unit its positional information.